The second shape is not a cyclic quadrilateral. One vertex does not touch the circumference. The opposite angles in a cyclic quadrilateral add up to 180°.

It’s no wonder that farmers with fields in the plains surrounding Stonehenge, in southern England, face late-summer mornings with dread. On any given day at the height of the growing season, as many ...

Take any quadrilateral such as ABCD above. Construct the midpoints of each side and join them to form another quadrilateral EFGH. Varignon's Theorem asserts that the ...

The world of geometry just witnessed a pivotal breakthrough. Mathematicians at Monash University have cracked a centuries-old puzzle dating back to the 17th century, extending Descartes’ Circle ...